1. The Field of the Invention
The present invention relates to structures for admitting sunlight and air into the interior of a building and, more particularly, is directed to energy efficient air flow windows and skylight structures having a self-contained fan and ventilating system.
2. In the Prior Art
The use of windows and skylights in buildings is an ancient practice which was developed to bring into a building the daylight, the heat, the ventilation, and the beauty of the out-of-doors. Additionally, windows and skylights provide aesthetic, psychological, and physiological benefits for humans and other animals.
While windows and skylights have several advantages, they are also disadvantageous in many respects. Historically, windows have not been as thermally efficient as the other structural elements of a building. Thus, during the cold winter months, a significant portion of the heat loss from the building occurs through the windows.
In addition, during the hot summer months, the building can experience excessive heat gain caused by solar radiant heat. This excess heat must be removed by air conditioning units which utilize energy at the highest cost level. In addition, sunlight passing through windows can cause fading of furnishings and discomfort to the occupants of the building from the glare and exposure of their bodies to direct solar radiation.
Because of the current high cost of energy, efforts have been made to develop methods for reducing the heat loss in winter and heat gain in summer which occurs through windows and skylights. Drapes and curtains have long been used as a method of blocking out direct solar radiation. While this can reduce the fading of furnishings and the discomfort caused by glare, drapes and curtains are not very effective at reducing heat loss and heat gain.
Tinted windows have been developed to reduce the amount of solar radiant heat which can enter the building, but their effect is minimal. Additionally, double and triple pane windows have been utilized to increase the thermal barrier to prevent heat loss or gain caused by the difference in indoor and outdoor temperatures.
A significant improvement in the energy efficiency of windows came with the development of the air flow window. These windows include at least two panes of glass with an air space formed therebetween. A stream of air is circulated through the space between the windows and becomes an integral part of the heating-ventilating-air conditioning system (hereinafter sometimes referred to as the "HVAC system") of the building. Venetian or other types of blinds can be included in the space between the windows to shade the interior of the building and to absorb the sun's radiant heat. The heat can then be transferred to the air flowing through the window and thence into the HVAC system of the building where it assists in heating during the winter and where it can be ventilated during the summer to reduce the heat gain.
While air flow windows have proven to be a major advancement in the development of energy efficient windows, they have not found wide acceptance in small buildings or in existing buildings for several reasons. First, an extensive engineering analysis is generally required to integrate the windows into the total HVAC system. These calculations require the determination of the amount of heat which can be obtained or which must be disposed of depending upon the heating or cooling needs of the building. Second, it is necessary to run ducts to each of the windows in order to collect the air and transfer it to the HVAC system. This significantly adds to the cost of a new building and is almost impossible to perform when retrofitting an existing structure.
Accordingly, what is needed in the art is an energy efficient window and skylight which can take advantage of enclosed blinds and an air flow system which does not need to be incorporated into the HVAC system of the building. It would be a further advancement in the art to provide such a window and skylight which could be used in existing structures as a replacement item as well as in new building construction. Such apparatus are disclosed and claimed herein.